Electrospun PEO-Based Composite Polymer Electrolyte with MOF Modified LLZTO for Solid-State Lithium Batteries

Solid polymer electrolytes have emerged as one of the most promising solid electrolytes due to their excellent flexibility and interfacial contact. However, their practical applications are hindered by low ionic conductivity and Li dendrite growth. Herein, metal–organic framework (ZIF-67) modified Li6.4La3Zr1.4Ta0.6O12 (LLZTO) were used as nanofillers (LZ) for PEO-based composite solid polymer electrolytes (CSPE). The electrospinning method was applied to promote the uniform dispersion of LZ particles in the film that helps to construct continuous Li+ transport channels. In addition, the ZIF-67 interact with both ether oxygen in PEO and anion in Li salt and can release more free lithium ions, thereby significantly enhancing the ionic conductivity (1.39 × 10–4 S cm–1, RT) and the Li+ transference number (0.62). The Li/Li symmetric cell continuously cycled without short-circuiting for a long duration over 2000 h, proving the high interface stability of Li-solid electrolyte. The Li/CSPE-LZ/LiFePO4 full cell delivered an initial discharge capacity of 154.3 mA h g–1 at 1 C, with a capacity retention rate of 95.4% after 220 cycles, demonstrating the feasibility of this CSPE for high performance all-solid-state lithium metal batteries.